The appointment of Susan Rice as national security advisor sends an important signal about the kind of foreign policy President Obama wants to pursue for the remainder of his second term: activist, assertive, occasionally even pugnacious. With three years to shape a legacy in world affairs, Obama wants to play offense, not defense.

For much of his first term, Obama's foreign policy was dominated by problems he inherited from George W. Bush: ending the U.S. war in Iraq, winding down the U.S. war in Afghanistan and continuing — indeed, escalating — the drone war against Al Qaeda and its allies.

Obama added some initiatives of his own, but they didn't all turn out well. He made a poorly conceived attempt to restart peace talks between Israel and the Palestinians; it failed. He sought a "reset" with Vladimir Putin's Russia; it didn't stick. He tightened sanctions against Iran and began negotiations, but Tehran's nuclear program is still grinding away.

So when he ran for reelection, Obama had little to trumpet beyond having killed Osama bin Laden and extracting us from Iraq. That was enough to help win a second term, but it isn't the epitaph he'd like to see in the history books.

Obama's first-term foreign policy team was partly designed to be defensive. The new-generation president had campaigned against the foreign policy establishment that got us into Iraq. But once in office, he hardly sought out visionary thinkers. Instead, he appointed reassuring establishment figures such as Hillary Rodham Clinton and Robert M. Gates.

His national security advisor, Thomas E. Donilon, was nearly invisible, but he made the foreign policy process work. Most recent presidents — Jimmy Carter, Ronald Reagan, Bill Clinton, George W. Bush — ran into internal chaos and external disasters in their first terms. Obama's first four years weren't perfect, but by comparison they look pretty good.

For his second term, though, Obama no longer needs a mythical "team of rivals" to counterbalance his inexperience. Instead, he's appointed people he's long been close to: former Senate colleagues John F. Kerry and Chuck Hagel, and one of his first campaign advisors, Susan Rice.

Rice's style couldn't be more different from Donilon's. He was an obsessively cautious backroom operator; she's a brash, in-your-face policy debater.

"People know not to mess with me," she once told the authors of a book about powerful women, "and [if] they try, they will learn."

For insiders, the big question is whether Rice can sublimate her views enough to act as the "honest broker" a national security advisor is supposed to be. She has a pronounced worldview, diplomats who have worked with her say, and she pursues it.

What's that worldview? Not surprisingly, it's a lot like Obama's. Rice believes in using U.S. power, but rarely unilaterally. In 2003, she was a skeptic about the cost and complexity of a war in Iraq, although not a full-throated opponent like Obama. In 2011, she was one of the key players who argued for U.S. military intervention in Libya — but only if it could be done with other countries, and a blessing from the U.N. Security Council.

Rice is particularly passionate about intervention to stop humanitarian disasters, a product of her experience on the NSC staff in 1994, when the Clinton administration failed to prevent the massacre of hundreds of thousands in Rwanda. "I swore to myself that if I ever faced such a crisis again, I would come down on the side of dramatic action, going down in flames if that was required," she said. Four years ago, she wept at a U.N. ceremony commemorating the genocide.

That doesn't mean Rice is now advocating U.S. military intervention in Syria, an idea Obama has resisted. Officials say both Obama and Rice are weighing the same practical question they faced in Libya two years ago: Would military action clearly produce a positive result? So far, the answer has been no.

But it does mean that Obama is comfortable enough with vigorous debate to put a strong proponent of humanitarian intervention at the top of his foreign policy team. And together with other moves, it suggests that Obama has an appetite for "throwing the occasional elbow but hitting the big shot," as he described Rice's style last week.

He's encouraged Kerry to try again to restart negotiations between Israel and the Palestinians, a strategy that insulates the president from blame if the long-shot attempt doesn't pay off.

He's moving toward a new round of nuclear arms reductions with Russia, a move that would save money and encourage cooperation from other countries on nonproliferation (although it would meet resistance from Republicans in Congress).

He's considering a comprehensive proposal to Iran to reduce economic sanctions and improve diplomatic relations in exchange for a verifiable freeze in Tehran's nuclear program, a last-ditch attempt to move those talks forward.

And there's still a long list of unfinished items from the first term: defining the complicated U.S. relationship with China, drawing down U.S. forces in Afghanistan, supporting the sputtering new democracies of the Arab Spring and preventing Syria's civil war from becoming a regional disaster.

A second term is a second chance, and Obama's choices for the top foreign policy jobs suggest that he intends to use it. The president's first-term focus was on recasting America's image after eight years of Bush, but it was also about minimizing risks on the way to reelection. In his second term, with that constraint gone, he appears ready to throw a few elbows.